3.6 Enthalpy changes

Question 1

What is enthalpy change of atomisation?

Answer 1

The enthalpy change when one mole of atoms of an element in the gas phase are formed from the element in its standard state under standard conditions

Question 2

What is the enthalpy change of lattice formation?

Answer 2

The enthalpy change when one mole of an ionic compound is formed from ions of the elements in the gas phase

Question 3

What is the enthalpy change of hydration?

Answer 3

enthalpy change when one mole of an ionic compound in solution is formed from ions of the elements in gas phase

Question 4

What is first electron affinity?

Answer 4

enthalpy change when one mole of gaseous negative ions are formed from the gaseous atoms of a substance by gaining an electron

Question 5

What is the enthalpy change of solution?

Answer 5

enthalpy change when one mole of a substance dissolves completely in a solvent under standard conditions to form a solution.
= enthalpy lattice breaking + enthalpy of hydration

latt breaking = endothermic, hydration= exothermic

Question 6

What two factors effect the enthalpy change of standard solution and why?

Answer 6

increasing the charge and size of ions increases the enthalpy of lattice breaking so increases the enthalpy of solution

Question 7

Is the enthalpy of lattice formation always endo or exothermic?

Answer 7

Exothermic
The more exothermic this is the more stable the ionic compound